NForce 630i w/ HD4890?

I don't know a whole lot about PC's, I always just bought prebuilt store ones, so just recently started reading more about PC's and how to build my own. I'm wanting to build a PC this summer for gaming, but right now I'm upgrading my store bought Acer.

I bought a new PSU, Corsair 750W & HD 4890 GPU. The issue I am having is with the motherboard that came with the PC. Under display adapters it is NVIDIA Geforce 7100 / NVIDIA nForce 630i (which is integrated gpu/mobo correct?)
While there is a slot to put the HD 4890, there are four little slots to the right of the slow that 2 other plugs go into, and they get in the way of the GPU, causing it to bed slightly at the back end, although only very slightly.
This is the closest picture I could find that somewhat resembles my motherboard: http://skinflint.co.uk/at/a325650.html although not exact it is pretty close.

My installed the GPU once and it had severe overheating problems(too hot to touch within a couple minutes after start up) and I sent it in for an exchange. Could the way the mobo is set up cause this problem, or any other problem in the near future? I plan to upgrade by summer but I want something that can last me until then.